Conservation of Mass/Thermal Energy in Chemical Reactions

What does the law of conservation of mass say about matter?

Answer explanation

Matter is neither created nor destroyed in a chemical reaction. The total number

of each type of atom is conserved; thus, the mass does not change.

Tags

NGSS.MS-PS1-5

Hydrogen peroxide is unstable under certain conditions and decomposes as shown to the left. What would be the result if we started with 40 grams of hydrogen peroxide?

Answer explanation

40 grams total of water and Oxygen

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Students are designing an experiment to test the law of conservation of mass using the following materials: 10 g baking soda, 30 mL vinegar, an electronic balance, and a resealable plastic bag. Describe the basic procedure the students should follow to model the law.

Answer explanation

Students should first measure the masses of all components separately. Then, they should combine the vinegar and baking soda in the plastic bag and seal it closed. Next they should mix the contents and find the mass of the combined materials according to the law of conservation of mass. The mass of the combining material should equal the mass of the individual components.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

What does a chemical equation show?

Answer explanation

the atoms' numbers & molecules that make up the reactants & products of a chemical reaction

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NGSS.MS-PS1-5

NGSS.MS-PS1-2

NGSS.MS-PS1-1

A student is using the following key to model the chemical equation provided. The reactants are on the left and the products are on the right. How many blue beads will the student need to model each side of the equation?

• 2 for the products and 2 for the reactants

• 1 for the products and 2 for the reactants

• 1 for the products and 1 for the reactants

• 2 for the products and 1 for the reactants

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-1

Students want to gather evidence for the claim that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction. They decide to react vinegar and baking soda in a sealed plastic bag. Which of the following would provide the evidence the students need?

• Bubbles were produced during the reaction, which meant that a gas was being produced.

• The mass of baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

• The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.

• The plastic bag did not change in any way, indicating that it was not involved in the reaction.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Which of the following is true regarding the atoms involved in the chemical reaction?

• 
  Some of the atoms present before the reaction will always be lost during a chemical reaction.

• During a chemical reaction, atoms will always be combined into much larger molecules.

• The same number of each type of atom will always be present before and after a chemical reaction takes place.

• Some of the atoms will always be changed into a different type of atom by a chemical reaction.

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NGSS.MS-PS1-5

In a chemical reaction known as decomposition, carbonic acid breaks down into water, and what other compound?

• 
• 
• 
• 

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NGSS.MS-PS1-5

NGSS.MS-PS1-2

Which of the following atomic models of chemical reactions correctly demonstrates the Law of Conservation of Matter?

• 
• 
• 
• 

Tags

NGSS.MS-PS1-5

Match the following

• Atom

• When atoms of substances rearrange themselves into a new configuration

• Mass

• To prevent the loss of something

• Law of conservation of mass

• 
  How much matter is in an object

• Conserve

• The smallest part of all matter

• Chemical reaction

• The total number of atoms of each element is not changed during a chemical reaction

Tags

NGSS.MS-PS1-5